This type of device is known from and disclosed in EP Patent No. A-1544691. In that document, the timepiece includes an hour hand able to be moved forward through one-hour steps by means of a manually actuated time-setting stem without affecting the minute display. In order to do so, the hour hand is constantly coupled to the going train, i.e. to the motor element carried by the timepiece except at the moment when the time is set when said hand is uncoupled from the going train, the rotation of the stem then moving said hand forward one hour. This system avoids affecting the hour decimals, which are preserved. For example, if the hour hand indicates 10 hours and 30 minutes, the rotation of the stem will move the hand forward to 11 hours and 30 minutes.
In order achieve this result the timepiece disclosed in the aforecited document includes a first wheel meshing with the gear train and a second wheel able to be driven by the stem when the time is being set. The wheels are coupled to each other by a limited torque mechanism including a spring. It will be clear that, outside periods when the time is being corrected, the first and second wheels remain rigidly coupled to each other, which allows the hour display to be altered without affecting the minutes that complete the hour.
Obtaining the same results, no longer from a stem that is rotated, but from a push-button that is pressed constitutes an advantageous technical advance since it means that a new timepiece can be proposed with combinations that are as yet unknown.
Using a push-button to correct certain time units is known. This is the case for the display of the date or the day of the week, which, for example, implements an actuating finger, which drives the toothing of a ring on which the date or day of the week is displayed which, appears through an aperture. However, this is a simple passage from one number to another, namely a step-by-step movement forward, where there is no need to take into account a fraction or a decimal of the number.